Watson was able to make the trailer by first analyzing 100 horror movie trailers, studying each scene, and looking for common ground. Next, it was fed the 90-minute movie, and chose 10 scenes that it thought would fit in the trailer. An editor then pieced together the scenes.

According to IBM:

“When we reviewed all the scenes that our system selected, one didn’t seem to fit with the bigger story we were trying to tell –so we decided not to use it. Even Watson sometimes ends up with footage on the cutting room floor!”

If you’re disappointed to see that it was not a purely-AI endeavor, you must know that making a trailer takes anywhere from 10 to 30 days. From the time Watson was fed the movie to the final cut of the trailer, it just took 24 hours.